<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    div{
      /*自定义初始值 2*/
      counter-reset: title 2;
    }
    h3:before{
      /*自定义步长 2*/
      counter-increment: title 2;
      /*自定义文字类型 数字,字母lower-latin,中文cjk-ideographic,罗马lower-roman*/
      /*希腊lower-greek*/
      content: 'title ' counter(title, lower-greek) ':';
    }
    h4:before{
      content: 'https://www.baidu.com'
    }
    ol,form{counter-reset: item;}
    li{display: block;}
    li:before{counter-increment: item;content:counters(item, '.') ' '}
    input:checked{
      counter-increment: item;
    }
    h5:before{
      content:counter(item)
    }
  </style>
</head>
<body>
<div>
  <h3>hello</h3>
  <h3>world</h3>
  <h3>javascript</h3>
</div>
<h4></h4>
<ol>
  <li>item1</li>
  <li>item2</li>
  <ol>
    <li>item2.1</li>
    <li>item2.2</li>
    <li>item2.3</li>
  </ol>
</ol>
<form action="">
  <input type="checkbox" value="1">包子
  <input type="checkbox" value="2">包子
  <input type="checkbox" value="3">包子
  <h5></h5>
</form>
</body>
</html>
